Configure DNS server to return same IP for all domains

Solution 1:

With BIND, you need a fake root zone to do this. In named.conf, put the following:

zone "." {
    type master;
    file "/etc/bind/db.fakeroot";
};

Then, in that db.fakeroot file, you will need something like the following:

@ IN SOA ns.domain.com. hostmaster.domain.com. ( 1 3h 1h 1w 1d )
  IN NS <ip>
* IN A <ip>

With that configuration, BIND will return the same IP address for all A queries.

Solution 2:

According to the dnsmasq man page

address=/#/1.2.3.4

should do the trick.